From Alan, didn't catch the author but....
4 laws of a Bot, not robot, Bot
First Law: A bot will always respond to input. Failure to respond should solely be an indication of hardware/software/connectivity failure.
Second Law: A bot will always be knowledgeable in the subjects it mentions in its answers, e.g., when a bot says, "Our widget works well with fish," the bot should be able to answer questions about fish and their relation to the widget.
Third Law: A bot will not repeat itself unduly (also, a bot will not repeat itself unduly). Any response which is likely to be elicited several times in a single conversation should be represented by multiple phrasings randomly.
Fourth Law: A bot will offer guidance when stumped. When presented with inputs that are not "understood," a bot should offer clues as to the inputs it can respond to authoritatively.